The Global Positioning System (GPS) and its extensions in the Global Navigation Satellite Systems (GNSS) have become thoroughly pervasive in all parts of human society, worldwide. GPS and GNSS receivers in the form of chipsets have become widely incorporated into cell phones and other types of cellular devices with cellular-based communications equipment.
Typically, cellular devices include highly integrated GPS/GNSS chipsets that are designed to work with the E-911 service primarily, and are not designed to provide anywhere near a full range of features and outputs. They do provide a position fix, but are not designed to make available very many other parameters of interest. All GPS/GNSS receivers must acquire, track and decode a data message that conveys information about the location of the satellites in space, and time information. The principal additional parameter obtained is the “pseudorange.” However, this set of data is not available as an output from the cell phone GPS chipsets for use by the cellular device itself. In circumstances where it is available, it is under access control by the vendor.